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  • 201. Mattsson, Tuve
    et al.
    Azhar, Shoaib
    KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center.
    Eriksson, Susanna
    Helander, Mikaela
    KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center.
    Henriksson, Gunnar
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology. KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center.
    Jedvert, Kerstin
    Lawoko, Martin
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology. KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center.
    Lindström, Mikael E.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology. KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center.
    McKee, Lauren S.
    KTH, School of Biotechnology (BIO), Glycoscience. KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center.
    Oinonen, Petri
    KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center.
    Sevastyanova, Olena
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology. KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center.
    Westerberg, Niklas
    Theliander, Hans
    The Development of a Wood-based Materials-biorefinery2017In: BioResources, ISSN 1930-2126, E-ISSN 1930-2126, Vol. 12, no 4, p. 9152-9182Article in journal (Refereed)
    Abstract [en]

    Several different methods for the extraction, separation, and purification of wood constituents were combined in this work as a unified process with the purpose of achieving a high overall efficiency of material extraction and utilization. This study aimed to present a laboratory-scale demonstrator biorefinery that illustrated how the different wood constituents could be separated from the wood matrix for later use in the production of new bio-based materials and chemicals by combining several approaches. This study builds on several publications and ongoing activities within the Wallenberg Wood Science Center (WWSC) in Sweden on the theme "From wood to material components." Combining the approaches developed in these WWSC projects - including mild steam explosion, membrane and chromatographic separation, enzymatic treatment and leaching, ionic liquid extraction, and fractionation together with Kraft pulping - formed an outline for a complete materials-biorefinery. The process steps involved were tested as integral steps in a linked process. The scale of operations ranged from the kilogram-scale to the gram-scale. The feasibility and efficiency of these process steps in a biorefinery system were assessed, based on the data, beginning with whole wood.

  • 202.
    McKee, Lauren S.
    KTH, School of Biotechnology (BIO), Glycoscience.
    Measuring enzyme kinetics of glycoside hydrolases using the 3,5-dinitrosalicylic acid assay2017In: Methods in Molecular Biology, Humana Press Inc. , 2017, p. 27-36Conference paper (Refereed)
    Abstract [en]

    Use of the 3,5-dinitrosalicylic acid reagent allows the simple and rapid quantification of reducing sugars. The method can be used for analysis of biological samples or in the characterization of enzyme reactions. Presented here is an application of the method in measuring the kinetics of a glycoside hydrolase reaction, including the optimization of the DNSA reagent, and the production of a standard curve of absorbance and sugar concentration.

  • 203.
    McKee, Lauren S.
    et al.
    KTH, School of Biotechnology (BIO), Glycoscience. KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center.
    Brumer, Harry
    KTH, School of Biotechnology (BIO), Glycoscience. KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center. Univ British Columbia, Canada.
    Growth of Chitinophaga pinensis on Plant Cell Wall Glycans and Characterisation of a Glycoside Hydrolase Family 27 beta-L-Arabinopyranosidase Implicated in Arabinogalactan Utilisation2015In: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 10, no 10, article id e0139932Article in journal (Refereed)
    Abstract [en]

    The genome of the soil bacterium Chitinophaga pinensis encodes a diverse array of carbohydrate active enzymes, including nearly 200 representatives from over 50 glycoside hydrolase (GH) families, the enzymology of which is essentially unexplored. In light of this genetic potential, we reveal that C. pinensis has a broader saprophytic capacity to thrive on plant cell wall polysaccharides than previously reported, and specifically that secretion of beta-L-arabinopyranosidase activity is induced during growth on arabinogalactan. We subsequently correlated this activity with the product of the Cpin_5740 gene, which encodes the sole member of glycoside hydrolase family 27 (GH27) in C. pinensis, CpArap27. Historically, GH27 is most commonly associated with alpha-D-galactopyranosidase and alpha-D-N-acetylgalactosaminidase activity. A new phylogenetic analysis of GH27 highlighted the likely importance of several conserved secondary structural features in determining substrate specificity and provides a predictive framework for identifying enzymes with the less common beta-L-arabinopyranosidase activity.

  • 204.
    McKee, Lauren S.
    et al.
    KTH, School of Biotechnology (BIO), Glycoscience. KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center.
    Sunner, Hampus
    Anasontzis, George E.
    Toriz, Guillermo
    Gatenholm, Paul
    Bulone, Vincent
    KTH, School of Biotechnology (BIO), Glycoscience. KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center. Univ Adelaide, Australia.
    Vilaplana, Francisco
    KTH, School of Biotechnology (BIO), Glycoscience. KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center.
    Olsson, Lisbeth
    A GH115 alpha-glucuronidase from Schizophyllum commune contributes to the synergistic enzymatic deconstruction of softwood glucuronoarabinoxylan2016In: Biotechnology for Biofuels, ISSN 1754-6834, E-ISSN 1754-6834, Vol. 9, article id 2Article in journal (Refereed)
    Abstract [en]

    Background: Lignocellulosic biomass from softwood represents a valuable resource for the production of biofuels and bio-based materials as alternatives to traditional pulp and paper products. Hemicelluloses constitute an extremely heterogeneous fraction of the plant cell wall, as their molecular structures involve multiple monosaccharide components, glycosidic linkages, and decoration patterns. The complete enzymatic hydrolysis of wood hemicelluloses into monosaccharides is therefore a complex biochemical process that requires the activities of multiple degradative enzymes with complementary activities tailored to the structural features of a particular substrate. Glucuronoarabinoxylan (GAX) is a major hemicellulose component in softwood, and its structural complexity requires more enzyme specificities to achieve complete hydrolysis compared to glucuronoxylans from hardwood and arabinoxylans from grasses. Results: We report the characterisation of a recombinant alpha-glucuronidase (Agu115) from Schizophyllum commune capable of removing (4-O-methyl)-glucuronic acid ((Me) GlcA) residues from polymeric and oligomeric xylan. The enzyme is required for the complete deconstruction of spruce glucuronoarabinoxylan (GAX) and acts synergistically with other xylan-degrading enzymes, specifically a xylanase (Xyn10C), an alpha-l-arabinofuranosidase (AbfA), and a beta-xylosidase (XynB). Each enzyme in this mixture showed varying degrees of potentiation by the other activities, likely due to increased physical access to their respective target monosaccharides. The exo-acting Agu115 and AbfA were unable to remove all of their respective target side chain decorations from GAX, but their specific activity was significantly boosted by the addition of the endo-Xyn10C xylanase. We demonstrate that the proposed enzymatic cocktail (Agu115 with AbfA, Xyn10C and XynB) achieved almost complete conversion of GAX to arabinofuranose (Araf), xylopyranose (Xylp), and MeGlcA monosaccharides. Addition of Agu115 to the enzymatic cocktail contributes specifically to 25 % of the conversion. However, traces of residual oligosaccharides resistant to this combination of enzymes were still present after deconstruction, due to steric hindrances to enzyme access to the substrate. Conclusions: Our GH115 alpha-glucuronidase is capable of finely tailoring the molecular structure of softwood GAX, and contributes to the almost complete saccharification of GAX in synergy with other exo- and endo-xylan-acting enzymes. This has great relevance for the cost-efficient production of biofuels from softwood lignocellulose.

  • 205. Mellroth, Peter
    et al.
    Sandalova, Tatyana
    Kikhney, Alexey
    Vilaplana, Francisco
    KTH, School of Biotechnology (BIO), Glycoscience.
    Hesek, Dusan
    Lee, Mijoon
    Mobashery, Shahriar
    Normark, Staffan
    Svergun, Dmitri
    Henriques-Normark, Birgitta
    Achour, Adnane
    Structural and Functional Insights into Peptidoglycan Access for the Lytic Amidase LytA of Streptococcus pneumoniae2014In: mBio, ISSN 2161-2129, E-ISSN 2150-7511, Vol. 5, no 1, p. e01120-13-Article in journal (Refereed)
    Abstract [en]

    The cytosolic N-acetylmuramoyl-L-alanine amidase LytA protein of Streptococcus pneumoniae, which is released by bacterial lysis, associates with the cell wall via its choline-binding motif. During exponential growth, LytA accesses its peptidoglycan substrate to cause lysis only when nascent peptidoglycan synthesis is stalled by nutrient starvation or beta-lactam antibiotics. Here we present three-dimensional structures of LytA and establish the requirements for substrate binding and catalytic activity. The solution structure of the full-length LytA dimer reveals a peculiar fold, with the choline-binding domains forming a rigid V-shaped scaffold and the relatively more flexible amidase domains attached in a trans position. The 1.05-angstrom crystal structure of the amidase domain reveals a prominent Y-shaped binding crevice composed of three contiguous subregions, with a zinc-containing active site localized at the bottom of the branch point. Site-directed mutagenesis was employed to identify catalytic residues and to investigate the relative impact of potential substrate-interacting residues lining the binding crevice for the lytic activity of LytA. In vitro activity assays using defined muropeptide substrates reveal that LytA utilizes a large substrate recognition interface and requires large muropeptide substrates with several connected saccharides that interact with all subregions of the binding crevice for catalysis. We hypothesize that the substrate requirements restrict LytA to the sites on the cell wall where nascent peptidoglycan synthesis occurs. IMPORTANCE Streptococcus pneumoniae is a human respiratory tract pathogen responsible for millions of deaths annually. Its major pneumococcal autolysin, LytA, is required for autolysis and fratricidal lysis and functions as a virulence factor that facilitates the spread of toxins and factors involved in immune evasion. LytA is also activated by penicillin and vancomycin and is responsible for the lysis induced by these antibiotics. The factors that regulate the lytic activity of LytA are unclear, but it was recently demonstrated that control is at the level of substrate recognition and that LytA required access to the nascent peptidoglycan. The present study was undertaken to structurally and functionally investigate LytA and its substrate-interacting interface and to determine the requirements for substrate recognition and catalysis. Our results reveal that the amidase domain comprises a complex substrate-binding crevice and needs to interact with a large-motif epitope of peptidoglycan for catalysis.

  • 206. Mikkonen, K. S.
    et al.
    Mathew, A. P.
    Pirkkalainen, K.
    Serimaa, R.
    Xu, Chunlin
    KTH, School of Biotechnology (BIO), Glycoscience. Åbo Akademi University.
    Willför, S.
    Oksman, K.
    Tenkanen, M.
    Glucomannan composite films with cellulose nanowhiskers2010In: Cellulose (London), ISSN 0969-0239, E-ISSN 1572-882X, Vol. 17, no 1, p. 69-81Article in journal (Refereed)
    Abstract [en]

    Spruce galactoglucomannans (GGM) and konjac glucomannan (KGM) were mixed with cellulose nanowhiskers (CNW) to form composite films. Remarkable effects of CNW on the appearance of the films were detected when viewed with regular and polarizing optical microscopes and with a scanning electron microscope. Addition of CNW to KGM-based films induced the formation of fiberlike structures with lengths of several millimeters. In GGM-based films, rodlike structures with lengths of several tens of micrometers were formed. The degree of crystallinity of mannan in the plasticized KGM-based films increased slightly when CNW were added, from 25 to 30%. The tensile strength of the KGM-based films not containing glycerol increased with increasing CNW content from 57 to 74 MPa, but that of glycerol-plasticized KGM and GGM films was not affected. Interestingly, the notable differences in the film structure did not appear to be related to the thermal properties of the films.

  • 207. Moberg, Tobias
    et al.
    Sahlin, Karin
    Yao, Kun
    KTH, School of Biotechnology (BIO), Glycoscience. KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center.
    Geng, Shiyu
    Westman, Gunnar
    Zhou, Qi
    KTH, School of Biotechnology (BIO), Glycoscience. KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center.
    Oksman, Kristiina
    Rigdahl, Mikael
    Rheological properties of nanocellulose suspensions: effects of fibril/particle dimensions and surface characteristics2017In: Cellulose (London), ISSN 0969-0239, E-ISSN 1572-882X, Vol. 24, no 6, p. 2499-2510Article in journal (Refereed)
    Abstract [en]

    The rheological properties of aqueous suspensions based on three different nanocelluloses were compared. One system was obtained via acid hydrolysis (thus yielding crystalline nanocellulose, CNC) and the other two from mechanical shearing, but from different origins and subjected to different pretreatments. Of the latter two, one was considered to be a rather typical cellulose nanofibril (CNF) suspension whereas the other was a kind of intermediate between CNF and CNC. All three nanocellulose elements differed in dimensions as evident from transmission electron microscopy and atomic force microscopy. With regard to the length of the fibrils/particles, the three nanocelluloses formed three distinct groups with lengths between 200 and slightly more than 800 nm. The three cellulosic elements were also subjected to a TEMPO-mediated oxidation yielding a similar carboxylate content in the three systems. Furthermore, the TEMPO-oxidized elements were grafted with poly(ethylene glycol) (PEG). The amount of grafted PEG was about 35 wt%. The shear viscosity, the storage modulus and the loss modulus of suspensions of the unmodified, the TEMPO-oxidized and the grafted nanocelluloses were determined at room temperature and the solids content of the suspensions was varied between 0.7 and 2.0 wt%. It was concluded that the rheological properties varied significantly between the suspensions depending on the dimensions of the cellulosic elements and their surface characteristics. In this context, the length (or the aspect ratio) of the particles played a very important role.

  • 208.
    Moberg, Tobias
    et al.
    Chalmers University of Technology, Sweden.
    Tang, Hu
    Zhou, Qi
    KTH, School of Biotechnology (BIO), Glycoscience. KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center.
    Rigdahl, Mikael
    KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center. Chalmers University of Technology, Sweden.
    Preparation and Viscoelastic Properties of Composite Fibres Containing Cellulose Nanofibrils: Formation of a Coherent Fibrillar Network2016In: Journal of Nanomaterials, ISSN 1687-4110, E-ISSN 1687-4129, Vol. 2016, article id 9569236Article in journal (Refereed)
    Abstract [en]

    Composite fibres with a matrix of poly(ethylene glycol) (PEG) and cellulose nanofibrils (CNF) as reinforcing elements were produced using a capillary viscometer. Two types of CNF were employed: one based on carboxymethylated pulp fibres and the other on TEMPO-oxidized pulp. Part of the latter nanofibrils was also grafted with PEG in order to improve the compatibility between the CNF and the PEG matrix. The nominal CNF-content was kept at 10 or 30 weight-%. The composite fibres were characterized by optical and scanning electron microscopy in addition to dynamic mechanical thermal analysis (DMTA). Evaluation of the storage modulus indicated a clear reinforcing effect of the CNF, more pronounced in the case of the grafted CNF and depending on the amount of CNF. An interesting feature observed during the DMTA-measurements was that the fibrils within the composite fibres appeared to forma rather coherent and load-bearing network which was evident even after removing of the PEG-phase (by melting). An analysis of the modulus of the composite fibres using a rather simple model indicated that the CNF were more efficient as reinforcing elements at lower concentrations which may be associated with a more pronounced aggregation as the volume fraction of CNF increased.

  • 209. Monegal, A.
    et al.
    Bulone, Vincent
    KTH, School of Biotechnology (BIO), Glycoscience.
    Planas, A.
    Enzymatic characterization of bovine alpha-1,3-galactosyltransferase. Validation of a radiometric assay and kinetic mechanism2005In: Afinidad, ISSN 0001-9704, Vol. 62, no 519, p. 505-512Article in journal (Refereed)
    Abstract [es]

    alpha 3-Galactosyltransferase (alpha 3GT) transfers galactose from UDP-Gal (sugar nucleotide donor) to the N-acetyllactosaminyl or lactosyl terminal groups of glycoproteins and glycolipids, catalyzing the formation of an alpha-1,3 glycosidic bond. The terminal saccharide Gal alpha 3NAcGal beta 4Glu-R is the main antigenic determinant responsible of the hyperaccute rejection in xenotransplantation. A radiometric assay for the determination of alpha 3GT activity is implemented and validated. The recombinant enzyme (catalytic domain) expressed in Eschericia coli follows a bi bi sequential ordered kinetic mechanism with binding of donor substrate (UDP-Gal) first and acceptor substrate to form a productive ternary complex. K-M values are 30 mu M for UDP-Gal, and 1.2 mM for lactose.

  • 210.
    Morais de Carvalho, Danila
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Abad, Antonio Martinez
    KTH, School of Biotechnology (BIO), Glycoscience.
    Evtuguin, D. V.
    Colodette, J. L.
    Lindström, Mikael
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Vilaplana, Francisco
    KTH, School of Biotechnology (BIO), Glycoscience.
    Sevastyanova, Olena
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Isolation and characterization of acetylated glucuronoarabinoxylan from sugarcane bagasse and straw2017In: Carbohydrate Polymers, ISSN 0144-8617, E-ISSN 1879-1344, Vol. 156, p. 223-234Article in journal (Refereed)
    Abstract [en]

    Sugarcane bagasse and straw are generated in large volumes as by-products of agro-industrial production. They are an emerging valuable resource for the generation of hemicellulose-based materials and products, since they contain significant quantities of xylans (often twice as much as in hardwoods). Heteroxylans (yields of ca 20% based on xylose content in sugarcane bagasse and straw) were successfully isolated and purified using mild delignification followed by dimethyl sulfoxide (DMSO) extraction. Delignification with peracetic acid (PAA) was more efficient than traditional sodium chlorite (NaClO2) delignification for xylan extraction from both biomasses, resulting in higher extraction yields and purity. We have shown that the heteroxylans isolated from sugarcane bagasse and straw are acetylated glucuronoarabinoxylans (GAX), with distinct molecular structures. Bagasse GAX had a slightly lower glycosyl substitution molar ratio of Araf to Xylp to (0.5:10) and (4-O-Me)GlpA to Xylp (0.1:10) than GAX from straw (0.8:10 and 0.1:10 respectively), but a higher degree of acetylation (0.33 and 0.10, respectively). A higher frequency of acetyl groups substitution at position α-(1 → 3) (Xyl-3Ac) than at position α-(1 → 2) (Xyl-2Ac) was confirmed for both bagasse and straw GAX, with a minor ratio of diacetylation (Xyl-2,3Ac). The size and molecular weight distributions for the acetylated GAX extracted from the sugarcane bagasse and straw were analyzed using multiple-detection size-exclusion chromatography (SEC-DRI-MALLS). Light scattering data provided absolute molar mass values for acetylated GAX with higher average values than did standard calibration. Moreover, the data highlighted differences in the molar mass distributions between the two isolation methods for both types of sugarcane GAX, which can be correlated with the different Araf and acetyl substitution patterns. We have developed an empirical model for the molecular structure of acetylated GAX extracted from sugarcane bagasse and straw with PAA/DMSO through the integration of results obtained from glycosidic linkage analysis, 1H NMR spectroscopy and acetyl quantification. This knowledge of the structure of xylans in sugarcane bagasse and straw will provide a better understanding of the isolation-structure-properties relationship of these biopolymers and, ultimately, create new possibilities for the use of sugarcane xylan in high-value applications, such as biochemicals and bio-based materials. © 2016 Elsevier Ltd

  • 211.
    Moraisde Carvalho, Danila
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology. Univ Fed Vicosa, Dept Forestry Engn, Pulp & Paper Lab, BR-36570900 Vicosa, MG, Brazil.
    Martinez Abad, Antonio
    KTH, School of Biotechnology (BIO), Glycoscience.
    Colodette, Jorge Luiz
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
    Lindström, Mikael
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
    Vilaplana, Fransisco
    KTH, School of Biotechnology (BIO), Glycoscience. KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center.
    Sevastyanova, Olena
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology. KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center.
    Comparative characterization of acetylated heteroxylan from eucalyptus, sugarcane bagasse and sugarcane strawManuscript (preprint) (Other academic)
  • 212. Moreno, Roberta B.
    et al.
    Ruthes, Andrea Caroline
    KTH, School of Biotechnology (BIO), Glycoscience. Universidade Federal Do Paraná, Brazil.
    Baggio, Cristiane H.
    Vilaplana, Francisco
    KTH, School of Biotechnology (BIO), Glycoscience.
    Komura, Dirce L.
    Iacomini, Marcello
    Structure and antinociceptive effects of beta-D-glucans from Cookeina tricholoma2016In: Carbohydrate Polymers, ISSN 0144-8617, E-ISSN 1879-1344, Vol. 141, p. 220-228Article in journal (Refereed)
    Abstract [en]

    Structurally different water-insoluble (1 -> 3),(1 -> 6) beta-D-glucans were isolated from aqueous and alkaline extracts of the mushroom-forming ascomycete Cookeina tricholoma, a wild edible mushroom found in Brazilian Amazon forest. The structures showed different substitution patterns, which may influence their extractability and consequently their conformation in solution, and different M-w (4.3 x 10(5) Da, 3.7 x 10(5) Da and 8.2 x 10(5) Da, for ICW-Ct, IHW-Ct and IK2-ct, respectively). The main-chains are composed of (1 -> 3) -linked beta-D-Glcp units 0-6 substituted by side chains with different lengths of (1 -> 6)-linked beta-D-Glcp units (ICW-Ct and IHW-Ct) or by a combination of (1 -> 6) -linked beta-D-Glcp units and single units of beta-D-Glcp (IK2-ct). beta-D-glucans with similar Mw and showing only (1 6) -linked beta-D-Glcp units as side chains (ICW-Ct and IHW-Ct) showed significant inhibition of neurogenic pain, 69 +/- 11 and 57 +/- 11% at the dose of 10 mg kg(-1), respectively, in the model of nociception induced by intraplantar injection of formalin.

  • 213.
    Moriana, Rosana
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
    Vilaplana, Francisco
    KTH, School of Biotechnology (BIO), Glycoscience. KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center.
    Ek, Monica
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
    Cellulose Nanocrystals from Forest Residues as Reinforcing Agents for Composites: A Study from Macro- to Nano-Dimensions2016In: Carbohydrate Polymers, ISSN 0144-8617, E-ISSN 1879-1344, Vol. 139, p. 139-149Article in journal (Refereed)
    Abstract [en]

    This study investigates for the first time the feasibility of extracting cellulose nanocrystals (CNCs) from softwood forestry logging residues (woody chips, branches and pine needles), with an obtained gravimetric yield of over 13%. Compared with the other residues, woody chips rendered a higher yield of bleached cellulosic fibers with higher hemicellulose, pectin and lignin content, longer diameter, and lower crystallinity and thermal stability. The isolation of CNCs from these bleached cellulosic fibers was verified by the removal of most of their amorphous components, the increase in the crystallinity index, and the nano-dimensions of the individual crystals. The differences in the physico-chemical properties of the fibers extracted from the three logging residues resulted in CNCs with specific physico-chemical properties. The potential of using the resulting CNCs as reinforcements in nanocomposites was discussed in terms of aspect ratio, crystallinity and thermal stability.

  • 214.
    Moriana, Rosana
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology. Instituto de Tecnología de Materiales (ITM), Escuela Técnica Superior de Ingeniería Del Diseño (ETSID), Universidad Politécnica, Spain.
    Vilaplana, Francisco
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology. KTH, School of Biotechnology (BIO), Glycoscience. KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center.
    Karlsson, Sigbritt
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology. University of Skövde, Sweden .
    Ribes, Amparo
    Correlation of chemical, structural and thermal properties of natural fibres for their sustainable exploitation2014In: Carbohydrate Polymers, ISSN 0144-8617, E-ISSN 1879-1344, Vol. 112, p. 422-431Article in journal (Refereed)
    Abstract [en]

    The potential of lignocellulosic natural fibres as renewable resources for thermal conversion and material reinforcement is largely dependent on the correlation between their chemical composition, crystalline structure and thermal decomposition properties. Significant differences were observed in the chemical composition of cotton, flax, hemp, kenaf and jute natural fibres in terms of cellulose, hemicellulose and lignin content, which influence their morphology, thermal properties and pyrolysis product distribution. A suitable methodology to study the kinetics of the thermal decomposition process of lignocellulosic fibres is proposed combining different models (Friedman, Flynn-Wall-Ozawa, Criado and Coats-Redfern). Cellulose pyrolysis can be modelled with similar kinetic parameters for all the natural fibres whereas the kinetic parameters for hemicellulose pyrolysis show intrinsic differences that can be assigned to the heterogeneous hemicellulose sugar composition in each natural fibre. This study provides the ground to critically select the most promising fibres to be used either for biofuel or material applications.

  • 215.
    Moriana, Rosana
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Vilaplana, Francisco
    KTH, School of Biotechnology (BIO), Glycoscience.
    Zhang, Yujia
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Ek, Monica
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Using waste biomass to obtain a renewable nanocomposite based on cellulosic biofibre and cereal wall polymers2013In: Abstract of Papers of the American Chemical Society, ISSN 0065-7727, Vol. 245Article in journal (Other academic)
  • 216.
    Mushi, Ngesa Ezekiel
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Butchosa, Nuria
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Salajkova, Michaela
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Zhou, Qi
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology. KTH, School of Biotechnology (BIO), Glycoscience.
    Berglund, Lars A.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology. KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center.
    Nanostructured membranes based on native chitin nanofibers prepared by mild process2014In: Carbohydrate Polymers, ISSN 0144-8617, E-ISSN 1879-1344, Vol. 112, p. 255-263Article in journal (Refereed)
    Abstract [en]

    Procedures for chitin nanofiber or nanocrystal extraction from Crustaceans modify the chitin structure significantly, through surface deacetylation, surface oxidation and/or molar mass degradation. Here, very mild conditions were used to disintegrate chitin fibril bundles and isolate low protein content individualized chitin nanofibers, and prepare nanostructured high-strength chitin membranes. Most of the strongly 'bound' protein was removed. The degree of acetylation, crystal structure as well as length and width of the native chitin microfibrils in the organism were successfully preserved. Atomic force microscopy and scanning transmission electron microscopy, showed chitin nanofibers with width between 3 and 4 nm. Chitin membranes were prepared by filtration of hydrocolloidal nanofiber suspensions. Mechanical and optical properties were measured. The highest data so far reported for nanostructured chitin membranes was obtained for ultimate tensile strength, strain to failure and work to fracture. Strong correlation was observed between low residual protein content and high tensile properties and the reasons for this are discussed.

  • 217.
    Mushi, Ngesa Ezekiel Zekiel
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Kochumalayil, Joby J.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Cervin, Nicholas Tchang Chang
    KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center.
    Zhou, Qi
    KTH, School of Biotechnology (BIO), Glycoscience.
    Berglund, Lars A.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Nanostructurally Controlled Hydrogel Based on Small-Diameter Native Chitin Nanofibers: Preparation, Structure, and Properties2016In: ChemSusChem, ISSN 1864-5631, E-ISSN 1864-564XArticle in journal (Refereed)
    Abstract [en]

    Chitin nanofibers of unique structure and properties can be obtained from crustacean and fishery waste. These chitin nanofibers have roughly 4nm diameters, aspect ratios between 25-250, a high degree of acetylation and preserved crystallinity, and can be potentially applied in hydrogels. Hydrogels with a chitin nanofiber content of 0.4, 0.6, 0.8, 1.0, 2.0, and 3.0wt% were successfully prepared. The methodology for preparation is new, environmentally friendly, and simple as gelation is induced by neutralization of the charged colloidal mixture, inducing precipitation and secondary bond interaction between nanofibers. Pore structure and pore size distributions of corresponding aerogels are characterized using auto-porosimetry, revealing a substantial fraction of nanoscale pores. To the best of our knowledge, the values for storage (13kPa at 3wt%) and compression modulus (309kPa at 2wt%) are the highest reported for chitin nanofibers hydrogels.

  • 218.
    Mushi, Ngesa Ezekiel
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Zhou, Qi
    KTH, School of Biotechnology (BIO), Glycoscience. KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center.
    Berglund, Lars A.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology. KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center.
    Membrane and hydrogel properties from chitin fibril structures: Structure and properties at neutral pH2014In: Abstract of Papers of the American Chemical Society, ISSN 0065-7727, Vol. 247, p. 21-CELL-Article in journal (Other academic)
  • 219.
    Mélida, Hugo
    et al.
    KTH, School of Biotechnology (BIO), Glycoscience.
    Sain, D.
    Stajich, J. E.
    Bulone, Vincent
    KTH, School of Biotechnology (BIO), Glycoscience.
    Deciphering the uniqueness of Mucoromycotina cell walls by combining biochemical and phylogenomic approaches2015In: Environmental Microbiology, ISSN 1462-2912, E-ISSN 1462-2920, Vol. 17, no 5, p. 1649-1662Article in journal (Refereed)
    Abstract [en]

    Most fungi from the Mucoromycotina lineage occur in ecosystems as saprobes, although some species are phytopathogens or may induce human mycosis. Mucoromycotina represent early diverging models that are most valuable for understanding fungal evolution. Here we reveal the uniqueness of the cell wall structure of the Mucoromycotina Rhizopus oryzae and Phycomyces blakesleeanus compared with the better characterized cell wall of the ascomycete Neurospora crassa. We have analysed the corresponding polysaccharide biosynthetic and modifying pathways, and highlight their evolutionary features and higher complexity in terms of gene copy numbers compared with species from other lineages. This work uncovers the presence in Mucoromycotina of abundant fucose-based polysaccharides similar to algal fucoidans. These unexpected polymers are associated with unusually low amounts of glucans and a higher proportion of chitin compared with N.crassa. The specific structural features are supported by the identification of genes potentially involved in the corresponding metabolic pathways. Phylogenomic analyses of genes encoding carbohydrate synthases, polysaccharide modifying enzymes and enzymes involved in nucleotide-sugar formation provide evidence for duplication events during evolution of cell wall metabolism in fungi. Altogether, the data highlight the specificity of Mucoromycotina cell walls and pave the way for a finer understanding of their metabolism.

  • 220.
    Mélida, Hugo
    et al.
    KTH, School of Biotechnology (BIO), Glycoscience.
    Sandoval-Sierra, Jose V.
    Dieguez-Uribeondo, Javier
    Bulone, Vincent
    KTH, School of Biotechnology (BIO), Glycoscience.
    Analyses of Extracellular Carbohydrates in Oomycetes Unveil the Existence of Three Different Cell Wall Types2013In: Eukaryotic Cell, ISSN 1535-9778, E-ISSN 1535-9786, Vol. 12, no 2, p. 194-203Article in journal (Refereed)
    Abstract [en]

    Some of the most devastating plant and animal pathogens belong to the oomycete class. The cell walls of these microorganisms represent an excellent target for disease control, but their carbohydrate composition is elusive. We have undertaken a detailed cell wall analysis in 10 species from 2 major oomycete orders, the Peronosporales and the Saprolegniales, thereby unveiling the existence of 3 clearly different cell wall types: type I is devoid of N-acetylglucosamine (GlcNAc) but contains glucuronic acid and mannose; type II contains up to 5% GlcNAc and residues indicative of cross-links between cellulose and 1,3-beta-glucans; type III is characterized by the highest GlcNAc content (>5%) and the occurrence of unusual carbohydrates that consist of 1,6-linked GlcNAc residues. These 3 cell wall types are also distinguishable by their cellulose content and the fine structure of their 1,3-beta-glucans. We propose a cell wall paradigm for oomycetes that can serve as a basis for the establishment of cell wall architectural models and the further identification of cell wall subtypes. This paradigm is complementary to morphological and molecular criteria for taxonomic grouping and provides useful information for unraveling poorly understood cell wall carbohydrate biosynthetic pathways through the identification and characterization of the corresponding enzymes.

  • 221. Nars, A.
    et al.
    Lafitte, C.
    Chabaud, M.
    Drouillard, S.
    Mélida, Hugo
    KTH, School of Biotechnology (BIO), Glycoscience.
    Danoun, S.
    Le Costaouëc, T.
    Rey, T.
    Benedetti, J.
    Bulone, Vincent
    KTH, School of Biotechnology (BIO), Glycoscience.
    Barker, D. G.
    Bono, J. -J
    Dumas, B.
    Jacquet, C.
    Heux, L.
    Fliegmann, J.
    Bottin, A.
    Aphanomyces euteiches Cell Wall Fractions Containing Novel Glucan-Chitosaccharides Induce Defense Genes and Nuclear Calcium Oscillations in the Plant Host Medicago truncatula2013In: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 8, no 9, p. e75039-Article in journal (Refereed)
    Abstract [en]

    N-acetylglucosamine-based saccharides (chitosaccharides) are components of microbial cell walls and act as molecular signals during host-microbe interactions. In the legume plant Medicago truncatula, the perception of lipochitooligosaccharide signals produced by symbiotic rhizobia and arbuscular mycorrhizal fungi involves the Nod Factor Perception (NFP) lysin motif receptor-like protein and leads to the activation of the so-called common symbiotic pathway. In rice and Arabidopsis, lysin motif receptors are involved in the perception of chitooligosaccharides released by pathogenic fungi, resulting in the activation of plant immunity. Here we report the structural characterization of atypical chitosaccharides from the oomycete pathogen Aphanomyces euteiches, and their biological activity on the host Medicago truncatula. Using a combination of biochemical and biophysical approaches, we show that these chitosaccharides are linked to β-1,6-glucans, and contain a β-(1,3;1,4)-glucan backbone whose β-1,3-linked glucose units are substituted on their C-6 carbon by either glucose or N-acetylglucosamine residues. This is the first description of this type of structural motif in eukaryotic cell walls. Glucan-chitosaccharide fractions of A. euteiches induced the expression of defense marker genes in Medicago truncatula seedlings independently from the presence of a functional Nod Factor Perception protein. Furthermore, one of the glucan-chitosaccharide fractions elicited calcium oscillations in the nucleus of root cells. In contrast to the asymmetric oscillatory calcium spiking induced by symbiotic lipochitooligosaccharides, this response depends neither on the Nod Factor Perception protein nor on the common symbiotic pathway. These findings open new perspectives in oomycete cell wall biology and elicitor recognition and signaling in legumes.

  • 222. Niculaes, Claudiu
    et al.
    Morreel, Kris
    Kim, Hoon
    Lu, Fachuang
    Mckee, Lauren S.
    KTH, School of Biotechnology (BIO), Glycoscience.
    Ivens, Bart
    Haustraete, Jurgen
    Vanholme, Bartel
    De Rycke, Riet
    Hertzberg, Magnus
    Fromm, Jörg
    Bulone, Vincent
    KTH, School of Biotechnology (BIO), Glycoscience.
    Polle, Andrea
    Ralph, John
    Boerjan, Wout
    Phenylcoumaran Benzylic Ether Reductase Prevents Accumulation of Compounds Formed under Oxidative Conditions in Poplar Xylem2014In: The Plant Cell, ISSN 1040-4651, E-ISSN 1532-298X, Vol. 26, no 9, p. 3775-3791Article in journal (Refereed)
    Abstract [en]

    Phenylcoumaran benzylic ether reductase (PCBER) is one of the most abundant proteins in poplar (Populus spp) xylem, but its biological role has remained obscure. In this work, metabolite profiling of transgenic poplar trees downregulated in PCBER revealed both the in vivo substrate and product of PCBER. Based on mass spectrometry and NMR data, the substrate was identified as a hexosylated 8-5-coupling product between sinapyl alcohol and guaiacylglycerol, and the product was identified as its benzyl-reduced form. This activity was confirmed in vitro using a purified recombinant PCBER expressed in Escherichia coli. Assays performed on 20 synthetic substrate analogs revealed the enzyme specificity. In addition, the xylem of PCBER-downregulated trees accumulated over 2000-fold higher levels of cysteine adducts of monolignol dimers. These compounds could be generated in vitro by simple oxidative coupling assays involving monolignols and cysteine. Altogether, our data suggest that the function of PCBER is to reduce phenylpropanoid dimers in planta to form antioxidants that protect the plant against oxidative damage. In addition to describing the catalytic activity of one of the most abundant enzymes in wood, we provide experimental evidence for the antioxidant role of a phenylpropanoid coupling product in planta.

  • 223. Nilsson, Anders K.
    et al.
    Johansson, Oskar N.
    Fahlberg, Per
    Kommuri, Murali
    Topel, Mats
    Bodin, Lovisa J.
    Sikora, Per
    Modarres, Masoomeh
    Ekengren, Sophia
    KTH, School of Biotechnology (BIO), Glycoscience.
    Nguyen, Chi T.
    Farmer, Edward E.
    Olsson, Olof
    Ellerstrom, Mats
    Andersson, Mats X.
    Acylated monogalactosyl diacylglycerol: prevalence in the plant kingdom and identification of an enzyme catalyzing galactolipid head group acylation in Arabidopsis thaliana2015In: The Plant Journal, ISSN 0960-7412, E-ISSN 1365-313X, Vol. 84, no 6, p. 1152-1166Article in journal (Refereed)
    Abstract [en]

    The lipid phase of the thylakoid membrane is mainly composed of the galactolipids mono-and digalactosyl diacylglycerol (MGDG and DGDG, respectively). It has been known since the late 1960s that MGDG can be acylated with a third fatty acid to the galactose head group (acyl-MGDG) in plant leaf homogenates. In certain brassicaceous plants like Arabidopsis thaliana, the acyl-MGDG frequently incorporates oxidized fatty acids in the form of the jasmonic acid precursor 12-oxo-phytodienoic acid (OPDA). In the present study we further investigated the distribution of acylated and OPDA-containing galactolipids in the plant kingdom. While acyl-MGDG was found to be ubiquitous in green tissue of plants ranging from non-vascular plants to angiosperms, OPDA-containing galactolipids were only present in plants from a few genera. A candidate protein responsible for the acyl transfer was identified in Avena sativa (oat) leaf tissue using biochemical fractionation and proteomics. Knockout of the orthologous gene in A. thaliana resulted in an almost total elimination of the ability to form both non-oxidized and OPDA-containing acyl-MGDG. In addition, heterologous expression of the A. thaliana gene in E. coli demonstrated that the protein catalyzed acylation of MGDG. We thus demonstrate that a phylogenetically conserved enzyme is responsible for the accumulation of acyl-MGDG in A. thaliana. The activity of this enzyme in vivo is strongly enhanced by freezing damage and the hypersensitive response.

  • 224. Nishikubo, Nobuyuki
    et al.
    Awano, Tatsuya
    Banasiak, Alicja
    Bourquin, Veronica
    Ibatullin, Farid
    Funada, Ryo
    Brumer, Harry
    KTH, School of Biotechnology (BIO), Glycoscience.
    Teeri, Tuula T.
    KTH, School of Biotechnology (BIO), Glycoscience.
    Hayashi, Takahisa
    Sundberg, Björn
    Mellerowicz, Ewa J.
    Xyloglucan endo-transglycosylase (XET) functions in gelatinous layers of tension wood fibers in poplar - A glimpse into the mechanism of the balancing act of trees2007In: Plant and Cell Physiology, ISSN 0032-0781, E-ISSN 1471-9053, Vol. 48, no 6, p. 843-855Article in journal (Refereed)
    Abstract [en]

    Tension wood is a specialized tissue of deciduous trees that functions in bending woody stems to optimize their position in space. Tension wood fibers that develop on one side of the stem have an increased potency to shrink compared with fibers on the opposite side, thus creating a bending moment. It is believed that the gelatinous (G) cell wall layer containing almost pure cellulose of tension wood fibers is pivotal to their shrinking. By analyzing saccharide composition and linkage in isolated G-layers of poplar, we found that they contain some matrix components in addition to cellulose, of which xyloglucan is the most abundant. Xyloglucan, xyloglucan endo-transglycosylase (XET) activity and xyloglucan endo-transglycosylase/hydrolase (XTH) gene products were detected in developing G-layers by labeling using CCRC-M1 monoclonal antibody, in situ incorporation of XXXG-SR and the polyclonal antibody to poplar PttXET16-34, respectively, indicating that xyloglucan is incorporated into the G-layer during its development. Moreover, several XTH transcripts were altered and were generally up-regulated in developing tension wood compared with normal wood. In mature G-fibers, XTH gene products were detected in the G-layers while the XET activity was evident in the adjacent S-2 wall layer. We propose that XET activity is essential for G-fiber shrinking by repairing xyloglucan cross-links between G- and S-2-layers and thus maintaining their contact. Surprisingly, XTH gene products and XET activity persisted in mature G-fibers for several years, suggesting that the enzyme functions after cell death repairing the cross-links as they are being broken during the shrinking process.

  • 225. Nishikubo, Nobuyuki
    et al.
    Takahashi, Junko
    Roos, Alexandra A.
    Derba-Maceluch, Marta
    Piens, Kathleen
    KTH, School of Biotechnology (BIO), Glycoscience.
    Brumer, Harry
    KTH, School of Biotechnology (BIO), Glycoscience.
    Teeri, Tuula T.
    KTH, School of Biotechnology (BIO), Glycoscience.
    Stalbrand, Henrik
    Mellerowicz, Ewa J.
    Xyloglucan endo-Transglycosylase-Mediated Xyloglucan Rearrangements in Developing Wood of Hybrid Aspen2011In: Plant Physiology, ISSN 0032-0889, E-ISSN 1532-2548, Vol. 155, no 1, p. 399-413Article in journal (Refereed)
    Abstract [en]

    Xyloglucan endo-transglycosylases (XETs) encoded by xyloglucan endo-transglycosylases/hydrolase (XTH) genes modify the xyloglucan-cellulose framework of plant cell walls, thereby regulating their expansion and strength. To evaluate the importance of XET in wood development, we studied xyloglucan dynamics and XTH gene expression in developing wood and modified XET activity in hybrid aspen (Populus tremula X tremuloides) by overexpressing PtxtXET16-34. We show that developmental modifications during xylem differentiation include changes from loosely to tightly bound forms of xyloglucan and increases in the abundance of fucosylated xyloglucan epitope recognized by the CCRC-M1 antibody. We found that at least 16 Populus XTH genes, all likely encoding XETs, are expressed in developing wood. Five genes were highly and ubiquitously expressed, whereas PtxtXET16-34 was expressed more weakly but specifically in developing wood. Transgenic up-regulation of XET activity induced changes in cell wall xyloglucan, but its effects were dependent on developmental stage. For instance, XET overexpression increased abundance of the CCRC-M1 epitope in cambial cells and xylem cells in early stages of differentiation but not in mature xylem. Correspondingly, an increase in tightly bound xyloglucan content was observed in primary-walled xylem but a decrease was seen in secondary-walled xylem. Thus, in young xylem cells, XET activity limits xyloglucan incorporation into the tightly bound wall network but removes it from cell walls in older cells. XET overexpression promoted vessel element growth but not fiber expansion. We suggest that the amount of nascent xyloglucan relative to XET is an important determinant of whether XET strengthens or loosens the cell wall.

  • 226.
    Nordgren, Niklas
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Eklöf, Jens
    KTH, School of Biotechnology (BIO), Glycoscience.
    Zhou, Qi
    KTH, School of Biotechnology (BIO), Glycoscience.
    Brumer, Harry
    KTH, School of Biotechnology (BIO), Glycoscience.
    Rutland, Mark W.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    CELL 260-Top-down grafting of xyloglucan to gold monitored by QCM-D and AFM: Enzymatic activity and interactions with cellulose2008Conference paper (Refereed)
    Abstract [en]

    This study focuses on the manufacture and characterisation of model surfaces consisting of end grafted xyloglucan (XG), a naturally occurring polysaccharide, onto a gold substrate. The now well-established XET-technology was utilised for enzymatic incorporation of a thiol moiety at one end of the xyloglucan backbone. This functionalised macromolecule was subsequently top-down grafted to gold, forming a thiol-bonded xyloglucan brush-like layer. The grafting was monitored in-situ with QCM-D and a significant difference in the adsorbed/grafted amount between unmodified xyloglucan and the thiol-functionalised polymer was observed. The grafted surface was demonstrated to be accessible to enzyme digestion using the plant endo-xyloglucanase TmNXG1. The nanotribological properties towards cellulose of the untreated crystal, brush modified surface and enzyme exposed surfaces were compared with a view to understanding the role of xyloglucan in friction reduction. Friction coefficients obtained by the AFM colloidal probe technique using a cellulose functionalised probe on the xyloglucan brush showed an increase of a factor of two after the enzyme digestion and this result is interpreted in terms of surface roughness. Finally, the brush is shown to exhibit binding to cellulose despite its highly oriented nature.

  • 227.
    Nordgren, Niklas
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Eklöf, Jens
    KTH, School of Biotechnology (BIO), Glycoscience.
    Zhou, Qi
    KTH, School of Biotechnology (BIO), Glycoscience.
    Brumer III, Harry
    KTH, School of Biotechnology (BIO), Glycoscience.
    Rutland, Mark
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Top-Down Grafting of Xyloglucan to Gold Monitored by QCM-D and AFM: Enzymatic Activity and Interactions with Cellulose2008In: Biomacromolecules, ISSN 1525-7797, E-ISSN 1526-4602, Vol. 9, no 3, p. 942-948Article in journal (Refereed)
    Abstract [en]

    This study focuses on the manufacture and characterisation of model surfaces consisting of end grafted xyloglucan (XG), a naturally occurring polysaccharide, onto a gold substrate.  The now well-established XET-technology was utilised for enzymatic incorporation of a thiol moiety at one end of the xyloglucan backbone.  This functionalised macromolecule was subsequently top-down grafted to gold, forming a thiol-bonded xyloglucan brush-like layer. The grafting was monitored in-situ with QCM-D and a significant difference in the adsorbed/grafted amount between unmodified xyloglucan and the thiol-functionalised polymer was observed.  The grafted surface was demonstrated to be accessible to enzyme digestion using the plant endo-xyloglucanase TmNXG1.  The nanotribological properties towards cellulose of the untreated crystal, brush modified surface and enzyme exposed surfaces were compared with a view to understanding the role of xyloglucan in friction reduction.  Friction coefficients obtained by the AFM colloidal probe technique using a cellulose functionalised probe on the xyloglucan brush showed an increase of a factor of two after the enzyme digestion and this result is interpreted in terms of surface roughness.  Finally, the brush is shown to exhibit binding to cellulose despite its highly oriented nature.

  • 228.
    Nordgren, Niklas
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Johansson, Erik
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Xu, Chunlin
    KTH, School of Biotechnology (BIO), Glycoscience.
    Wågberg, Lars
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Brumer, Harry
    KTH, School of Biotechnology (BIO), Glycoscience.
    Functionalized xyloglucan assemblies on gold: A prospective biomimetic anchor for cellulose2011In: Abstract of Papers of the American Chemical Society, ISSN 0065-7727, Vol. 241Article in journal (Other academic)
  • 229.
    Ohlsson, Anna B.
    et al.
    KTH, School of Biotechnology (BIO), Glycoscience.
    Djerbi, Soraya
    KTH, School of Biotechnology (BIO), Glycoscience.
    Winzell, Anders
    KTH, School of Biotechnology (BIO), Glycoscience.
    Bessueille, Laurence
    Ståldal, Veronika
    Li, Xinguo
    KTH, School of Biotechnology (BIO), Glycoscience.
    Blomqvist, Kristina
    KTH, School of Biotechnology (BIO), Glycoscience.
    Bulone, Vincent
    Teeri, Tuula T.
    KTH, School of Biotechnology (BIO), Glycoscience.
    Berglund, Torkel
    KTH, School of Biotechnology (BIO), Glycoscience.
    Cell suspension cultures of Populus tremula x P. tremuloides exhibit a high level of cellulose synthase gene expression that coincides with increased in vitro cellulose synthase activity.2006In: Protoplasma, ISSN 0033-183X, E-ISSN 1615-6102, Vol. 228, no 4, p. 221-9Article in journal (Refereed)
    Abstract [en]

    Compared to wood, cell suspension cultures provide convenient model systems to study many different cellular processes in plants. Here we have established cell suspension cultures of Populus tremula L. x P. tremuloides Michx. and characterized them by determining the enzymatic activities and/or mRNA expression levels of selected cell wall-specific proteins at the different stages of growth. While enzymes and proteins typically associated with primary cell wall synthesis and expansion were detected in the exponential growth phase of the cultures, the late stationary phase showed high expression of the secondary-cell-wall-associated cellulose synthase genes. Interestingly, detergent extracts of membranes from aging cell suspension cultures exhibited high levels of in vitro cellulose synthesis. The estimated ratio of cellulose to callose was as high as 50 : 50, as opposed to the ratio of 30 : 70 so far achieved with membrane preparations extracted from other systems. The increased cellulose synthase activity was also evidenced by higher levels of Calcofluor white binding in the cell material from the stationary-phase cultures. The ease of handling cell suspension cultures and the improved capacity for in vitro cellulose synthesis suggest that these cultures offer a new basis for studying the mechanism of cellulose biosynthesis.

  • 230. Oksanen, A.
    et al.
    Retulainen, E.
    Rantanen, T.
    Brumer, Harry
    KTH, School of Biotechnology (BIO), Glycoscience.
    Improving recyclability of chemical pulp by introducing non-charged cross-linked polysaccharide on fiber surface: Volume 12010In: 2010 TAPPI PEERS Conference and 9th Research Forum on Recycling, 2010, p. 59-87Conference paper (Refereed)
    Abstract [en]

    The effect of spray application of xyloglucan on strength and recyclability of bleached chemical pulp was studied. Xyloglucan alone and with a cross-linking chemical was applied on sheets made of unbeaten never-dried and once-dried virgin pulps. Recyclability of these pulps was evaluated based on the tensile strength of wet and dry handsheets. Dry strength measurements showed that the spray application reduces the loss of strength and bonding ability in recycling. The use of cross-linking chemical was found to be essential in enhancing both the wet and dry strength of the virgin and recycled pulps. The chemical application was efficient with both never-dried and once-dried pulps. Wet web strength results indicate that the amount of web breaks could be decreased in paper and board machines using recovered fibers by having cross-linked xyloglucan layer on fiber surface. Spray application was found to be an effective way to introduce non-charged chemicals into fiber network. As a consequence of improved fiber bonding the need of refining decreases which further improves the recyclability of fibers. In addition to xyloglucan also other polysaccharides, for example those provided by chemical or mechanical pulp mills, could be used for improving the recyclability and extending the lifetime of fiber material.

  • 231. Oksanen, Antti
    et al.
    Retulainen, Elias
    Brumer, Harry
    KTH, School of Biotechnology (BIO), Glycoscience. University of British Columbia, Canada .
    Bulky paper with good strength and smoothness?: Certainly!2014In: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 29, no 4, p. 725-731Article in journal (Refereed)
    Abstract [en]

    Increasing bulk is the first step toward resource-lean papermaking. Increasing the bulk tends to reduce strength and increase porosity and roughness; however, loss in strength could be compensated for via an increase in the specific strength of bonds. The increase in total surface area can have a positive influence on the porosity and smoothness of the paper. Results suggest that the bulk of fine paper can be increased by 20% and the critical paper properties maintained through selection of the kraft fibre type, control of the degree of hornification, addition of xyloglucan, and use of fines-rich mechanical pulp. In general, the results reported on here suggest that increasing bulk or reducing grammage is a challenging task but can be accomplished through simultaneous application of several unconventional measures.

  • 232. Oksanen, Antti
    et al.
    Timo, Rantanen
    Retulainen, Elias
    Salminen, Kristian
    Brumer, Harry
    KTH, School of Biotechnology (BIO), Glycoscience.
    Improving Wet Web Runnability and Paper Quality by an Uncharged Polysaccharide2011In: J BIOBASED MATER BIO, ISSN 1556-6560, Vol. 5, no 2, p. 187-191Article in journal (Refereed)
    Abstract [en]

    The effects of xyloglucan addition on wet web strength, drying tension and end product quality of bleached birch kraft pulps were examined with laboratory trials. Specific xyloglucan dosages were applied onto wet fibre networks by spraying. Laboratory sheets were prepared of never-dried and once-dried birch pulps. Wet sheet strength and drying characteristics were analysed using diverse analytical instruments. Structural, strength and surface properties of dry sheet samples were tested according to standard methods. Wet web strength and tension holding potential of test samples increased with the addition of xyloglucan, which is an indication of better wet web runnability. Xyloglucan also increased the drying tension. Besides enhanced runnability, xyloglucan treatment was also found to improve end product quality by improving smoothness and dry strength properties, and decreasing air permeability. Results indicate that xyloglucan treatment has greater strengthening potential with once-dried chemical pulp, whereas the effect with never-dried pulp was smaller. Never-dried fibre has high natural bonding ability when once-dried fibres re-swelling and thus bonding ability has deteriorated in drying process. Therefore, xyloglucan seems to have potential especially in recovering the strength properties of pulp with hornified cell walls, such as in recycled pulp. In general, these results can be exploited in paper and board machines for tailoring fibre networks for different product grades or special functional products.

  • 233. Omadjela, Okako
    et al.
    Narahari, Adishesh
    Strumillo, Joanna
    Mélida, Hugo
    KTH, School of Biotechnology (BIO), Glycoscience.
    Mazur, Olga
    Bulone, Vincent
    KTH, School of Biotechnology (BIO), Glycoscience.
    Zimmer, Jochen
    BcsA and BcsB form the catalytically active core of bacterial cellulose synthase sufficient for in vitro cellulose synthesis2013In: Proceedings of the National Academy of Sciences of the United States of America, ISSN 0027-8424, E-ISSN 1091-6490, Vol. 110, no 44, p. 17856-17861Article in journal (Refereed)
    Abstract [en]

    Cellulose is a linear extracellular polysaccharide. It is synthesized by membrane-embedded glycosyltransferases that processively polymerize UDP-activated glucose. Polymer synthesis is coupled to membrane translocation through a channel formed by the cellulose synthase. Although eukaryotic cellulose synthases function in macromolecular complexes containing several different enzyme isoforms, prokaryotic synthases associate with additional subunits to bridge the periplasm and the outer membrane. In bacteria, cellulose synthesis and translocation is catalyzed by the inner membrane-associated bacterial cellulose synthase (Bcs) A and BcsB subunits. Similar to alginate and poly-beta-1,6 N-acetylglucosamine, bacterial cellulose is implicated in the formation of sessile bacterial communities, termed biofilms, and its synthesis is likewise stimulated by cyclic-di-GMP. Biochemical studies of exopolysaccharide synthesis are hampered by difficulties in purifying and reconstituting functional enzymes. We demonstrate robust in vitro cellulose synthesis reconstituted from purified BcsA and BcsB proteins from Rhodobacter sphaeroides. Although BcsA is the catalytically active subunit, the membrane-anchored BcsB subunit is essential for catalysis. The purified BcsA-B complex produces cellulose chains of a degree of polymerization in the range 200-300. Catalytic activity critically depends on the presence of the allosteric activator cyclic-di-GMP, but is independent of lipid-linked reactants. Our data reveal feedback inhibition of cellulose synthase by UDP but not by the accumulating cellulose polymer and highlight the strict substrate specificity of cellulose synthase for UDP-glucose. A truncation analysis of BcsB localizes the region required for activity of BcsA within its C-terminal membrane-associated domain. The reconstituted reaction provides a foundation for the synthesis of biofilm exopolysaccharides, as well as its activation by cyclic-di-GMP.

  • 234.
    Osaku, Erica F.
    et al.
    Univ Estadual Oeste Parana, Ctr Ciencias Biol & Saude, Caixa Postal 711, BR-85819110 Cascavel, PR, Brazil..
    Menolli, Rafael A.
    Univ Estadual Oeste Parana, Ctr Ciencias Medicas & Farmaceut, Caixa Postal 711, BR-85819110 Cascavel, PR, Brazil..
    Costa, Claudia R. L. de M.
    Univ Estadual Oeste Parana, Ctr Ciencias Biol & Saude, Caixa Postal 711, BR-85819110 Cascavel, PR, Brazil..
    Tessaro, Fernando Henrique G.
    Univ Sao Paulo, Fac Ciencias Farmaceut, BR-05508000 Sao Paulo, SP, Brazil..
    de Melo, Renan H.
    Univ Estadual Oeste Parana, Ctr Ciencias Medicas & Farmaceut, Caixa Postal 711, BR-85819110 Cascavel, PR, Brazil..
    do Amaral, Alex E.
    Univ Fed Santa Catarina, Programa Pos Grad Farm, BR-88040900 Florianopolis, SC, Brazil..
    Duarte, Pericles A. D.
    Univ Estadual Oeste Parana, Ctr Ciencias Medicas & Farmaceut, Caixa Postal 711, BR-85819110 Cascavel, PR, Brazil..
    de Santana Filho, Arquimedes Paixao
    Univ Fed Parana, Dept Bioquim & Biol Mol, BR-81531990 Curitiba, PR, Brazil..
    Ruthes, Andrea Caroline
    KTH, School of Biotechnology (BIO), Glycoscience.
    Silva, Jose Luis da C.
    Univ Estadual Oeste Parana, Ctr Ciencias Medicas & Farmaceut, Caixa Postal 711, BR-85819110 Cascavel, PR, Brazil..
    Mello, Rosiane G.
    beta-(1 -> 6)-d-glucan secreted during the optimised production of exopolysaccharides by Paecilomyces variotii has immunostimulatory activity2018In: Antonie van Leeuwenhoek. International Journal of General and Molecular Microbiology, ISSN 0003-6072, E-ISSN 1572-9699, Vol. 111, no 6, p. 981-994Article in journal (Refereed)
    Abstract [en]

    Paecilomyces variotii is a filamentous fungus that occurs worldwide in soil and decaying vegetation. Optimization of the fermentation process for exopolysaccharide (EPS) production from the fungus P. variotii, structure determination and immuno-stimulating activity of EPS were performed. Response surface methodology (RSM) coupled with central composite design (CCD) was used to optimize the physical and chemical factors required to produce EPS in submerged fermentation. Preliminary investigations to choose the three factors for the present work were made using a factorial experimental design. Glucose, ammonium nitrate (NH4NO3) and pH were used as variables for which, with constant temperature of 28 A degrees C and agitation of 90 rpm, the optimal process parameters were determined as glucose values of 0.96%, NH4NO3 0.26% and pH 8.0. The three parameters presented significant effects. In this condition of culture, the main composition of the isolated EPS was a linear beta-(1 -> 6)-linked-D-glucan, as determined by Nuclear Magnetic Resonance (NMR) and methylation analysis. This polysaccharide is a very unusual as an EPS from fungi, especially a filamentous fungus such as P. variotii. Murine peritoneal macrophages cultivated with beta-glucan for 6 and 48 h showed an increase in TNF-alpha, IL-6 and nitric oxide release with increased polysaccharide concentrations. Therefore, we conclude that the beta-(1 -> 6)-linked-D-glucan produced in optimised conditions of P. variotii cultivation has an immune-stimulatory activity on murine macrophages.

  • 235. Pacheco-Villalobos, David
    et al.
    Diaz-Moreno, Sara M.
    KTH, School of Biotechnology (BIO), Glycoscience.
    van der Schuren, Alja
    Tamaki, Takayuki
    Kang, Yeon Hee
    Gujas, Bojan
    Novak, Ondrej
    Jaspert, Nina
    Li, Zhenni
    Wolf, Sebastian
    Oecking, Claudia
    Ljung, Karin
    Bulone, Vincent
    KTH, School of Biotechnology (BIO), Glycoscience.
    Hardtke, Christian S.
    The Effects of High Steady State Auxin Levels on Root Cell Elongation in Brachypodium2016In: The Plant Cell, ISSN 1040-4651, E-ISSN 1532-298X, Vol. 28, no 5, p. 1009-1024Article in journal (Refereed)
    Abstract [en]

    The long-standing Acid Growth Theory of plant cell elongation posits that auxin promotes cell elongation by stimulating cell wall acidification and thus expansin action. To date, the paucity of pertinent genetic materials has precluded thorough analysis of the importance of this concept in roots. The recent isolation of mutants of the model grass species Brachypodium distachyon with dramatically enhanced root cell elongation due to increased cellular auxin levels has allowed us to address this question. We found that the primary transcriptomic effect associated with elevated steady state auxin concentration in elongating root cells is upregulation of cell wall remodeling factors, notably expansins, while plant hormone signaling pathways maintain remarkable homeostasis. These changes are specifically accompanied by reduced cell wall arabinogalactan complexity but not by increased proton excretion. On the contrary, we observed a tendency for decreased rather than increased proton extrusion from root elongation zones with higher cellular auxin levels. Moreover, similar to Brachypodium, root cell elongation is, in general, robustly buffered against external pH fluctuation in Arabidopsis thaliana. However, forced acidification through artificial proton pump activation inhibits root cell elongation. Thus, the interplay between auxin, proton pump activation, and expansin action may be more flexible in roots than in shoots.

  • 236.
    Pallinti, Purushotham Naidu
    et al.
    Univ Virginia, Charlottesville, VA USA..
    Cho, Sung Hyun
    Penn State, Biochem & Mol Biol, University Pk, PA USA..
    Diaz-Moreno, Sara M.
    KTH, School of Biotechnology (BIO), Glycoscience.
    Kumar, Manish
    Penn State, Dept Chem Engn, University Pk, PA USA..
    Nixon, B. Tracy
    Penn State, Biochem & Mol Biol, University Pk, PA USA..
    Bulone, Vincent
    KTH, School of Biotechnology (BIO), Glycoscience. Royal Inst Technol, Div Glycosci, Stockholm, Sweden.;Australian Res Council Ctr Excellence Plant Cell, Sch Agr Food & Wine, Urrbrae, SA, Australia..
    Zimmer, Jochen
    Univ Virginia, Charlottesville, VA USA..
    Cellulose microfibril formation in vitro by a single heterologously expressed plant cellulose synthase isoform2017In: Abstract of Papers of the American Chemical Society, ISSN 0065-7727, Vol. 253Article in journal (Other academic)
  • 237.
    Pang, Zhili
    et al.
    KTH, School of Biotechnology (BIO), Glycoscience. China Agricultural University, China.
    Chen, Lei
    Miao, Jianqiang
    Wang, Zhiwen
    Bulone, Vincent
    KTH, School of Biotechnology (BIO), Glycoscience. University of Adelaide, Australia.
    Liu, Xili
    Proteomic profile of the plant-pathogenic oomycete Phytophthora capsici in response to the fungicide pyrimorph2015In: Proteomics, ISSN 1615-9853, E-ISSN 1615-9861, Vol. 15, no 17, p. 2972-2982Article in journal (Refereed)
    Abstract [en]

    Pyrimorph is a novel fungicide from the carboxylic acid amide (CAA) family used to control plant-pathogenic oomycetes such as Phytophthora capsici. The proteomic response of P. capsici to pyrimorph was investigated using the iTRAQ technology to determine the target site of the fungicide and potential biomarker candidates of drug efficacy. A total of 1336 unique proteins were identified from the mycelium of wild-type P. capsici isolate (Hd3) and two pyrimorphresistantmutants (R3-1 and R3-2) grown in the presence or absence of pyrimorph. Comparative analysis revealed that the three P. capsici isolates Hd3, R3-1, and R3-2 produced 163, 77, and 13 unique proteins, respectively, which exhibited altered levels of abundance in response to the pyrimorph treatment. Further investigations, using Cluster of Orthologous Groups of Proteins (COG) analysis and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis identified 35 proteins related to the mode of action of pyrimorph against P. capsici and 62 proteins involved in the stress response of P. capsici to pyrimorph. Many of the proteins with altered expression were associated with glucose and energy metabolism. Biochemical analysis using D-[U-C-14] glucose verified the proteomics data, suggesting that the major mode of action of pyrimorph in P. capsici is the inhibition of cell wall biosynthesis. These results also illustrate that proteomics approaches are useful tools for determining the pathways targeted by novel fungicides as well as for evaluating the tolerance of plant pathogens to environmental challenges, such as the presence of fungicides.

  • 238.
    Pang, Zhili
    et al.
    KTH, School of Biotechnology (BIO), Glycoscience.
    Srivastava, Vaibhav
    KTH, School of Biotechnology (BIO), Glycoscience.
    Liu, X.
    Bulone, Vincent
    KTH, School of Biotechnology (BIO), Glycoscience.
    Quantitative proteomics links metabolic pathways to specific developmental stages of the plant-pathogenic oomycete Phytophthora capsici2016In: Molecular plant pathology, ISSN 1464-6722, E-ISSN 1364-3703Article in journal (Refereed)
    Abstract [en]

    The oomycete Phytophthora capsici is a plant pathogen responsible for important losses to vegetable production worldwide. Its asexual reproduction plays an important role in the rapid propagation and spread of the disease in the field. A global proteomics study was conducted to compare two key asexual life stages of P. capsici, i.e. the mycelium and cysts, to identify stage-specific biochemical processes. A total of 1200 proteins was identified using qualitative and quantitative proteomics. The transcript abundance of some of the enriched proteins was also analysed by quantitative real-time polymerase chain reaction. Seventy-three proteins exhibited different levels of abundance between the mycelium and cysts. The proteins enriched in the mycelium are mainly associated with glycolysis, the tricarboxylic acid (or citric acid) cycle and the pentose phosphate pathway, providing the energy required for the biosynthesis of cellular building blocks and hyphal growth. In contrast, the proteins that are predominant in cysts are essentially involved in fatty acid degradation, suggesting that the early infection stage of the pathogen relies primarily on fatty acid degradation for energy production. The data provide a better understanding of P. capsici biology and suggest potential metabolic targets at the two different developmental stages for disease control. © 2016 BSPP AND JOHN WILEY & SONS LTD.

  • 239. Parikka, K.
    et al.
    Leppänen, A. -S
    Xu, Chunlin
    KTH, School of Biotechnology (BIO), Glycoscience. KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center.
    Pitkänen, L.
    Eronen, P.
    Österberg, M.
    Brumer, Harry
    KTH, School of Biotechnology (BIO), Glycoscience. KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center.
    Willför, S.
    Tenkanen, M.
    Functional and anionic cellulose-interacting polymers by selective chemo-enzymatic carboxylation of galactose-containing polysaccharides2012In: Biomacromolecules, ISSN 1525-7797, E-ISSN 1526-4602, Vol. 13, no 8, p. 2418-2428Article in journal (Refereed)
    Abstract [en]

    Carboxylated, anionic polysaccharides were selectively prepared using a combination of enzymatic and chemical reactions. The galactose-containing polysaccharides studied were spruce galactoglucomannan, guar galactomannan, and tamarind galactoxyloglucan. The galactosyl units of the polysaccharides were first oxidized with galactose oxidase (EC 1.1.3.9) and then selectively carboxylated, resulting in the galacturonic acid derivatives with good conversion and yield. The degrees of oxidation (DO) of the products were determined by gas chromatography-mass spectrometry (GC-MS). A novel feasible electrospray ionization-mass spectrometry (ESI-MS) method was also developed for the determination of DO. The solution properties and charge densities of the products were investigated. The interaction of the products with cellulose was studied by two methods, bulk sorption onto bleached birch kraft pulp and adsorption onto nanocellulose ultrathin films by quartz crystal microbalance with dissipation (QCM-D). To study the effect of the location of the carboxylic acid groups on the physicochemical properties, polysaccharides were also oxidized by 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO)-mediated reaction producing polyuronic acids. The chemo-enzymatically oxidized galacturonic polysaccharides with an unmodified backbone had a better ability to interact with cellulose than the TEMPO-oxidized products. The selectively carboxylated polysaccharides can be further exploited, as such, or in the targeted functionalization of cellulose surfaces.

  • 240. Park, Eunsook
    et al.
    Diaz-Moreno, Sara M.
    KTH, School of Biotechnology (BIO), Glycoscience.
    Davis, Destiny J.
    Wilkop, Thomas E.
    Bulone, Vincent
    KTH, School of Biotechnology (BIO), Glycoscience.
    Drakakaki, Georgia
    Endosidin 7 Specifically Arrests Late Cytokinesis and Inhibits Callose Biosynthesis, Revealing Distinct Trafficking Events during Cell Plate Maturation2014In: Plant Physiology, ISSN 0032-0889, E-ISSN 1532-2548, Vol. 165, no 3, p. 1019-1034Article in journal (Refereed)
    Abstract [en]

    Although cytokinesis is vital for plant growth and development, our mechanistic understanding of the highly regulated membrane and cargo transport mechanisms in relation to polysaccharide deposition during this process is limited. Here, we present an in-depth characterization of the small molecule endosidin 7 (ES7) inhibiting callose synthase activity and arresting late cytokinesis both in vitro and in vivo in Arabidopsis (Arabidopsis thaliana). ES7 is a specific inhibitor for plant callose deposition during cytokinesis that does not affect endomembrane trafficking during interphase or cytoskeletal organization. The specificity of ES7 was demonstrated (1) by comparing its action with that of known inhibitors such as caffeine, flufenacet, and concanamycin A and (2) across kingdoms with a comparison in yeast. The interplay between cell plate-specific post-Golgi vesicle traffic and callose accumulation was analyzed using ES7, and it revealed unique and temporal contributions of secretory and endosomal vesicles in cell plate maturation. While RABA2A-labeled vesicles, which accumulate at the early stage of cell plate formation, were not affected by ES7, KNOLLE was differentially altered by the small molecule. In addition, the presence of clathrin-coated vesicles in cells containing elevated levels of callose and their reduction under ES7 treatment further support the role of endocytic membrane remodeling in the maturing cell plate while the plate is stabilized by callose. Taken together, these data show the essential role of callose during the late stages of cell plate maturation and establish the temporal relationship between vesicles and regulatory proteins at the cell plate assembly matrix during polysaccharide deposition.

  • 241.
    Pavankumar, Asalapuram R.
    et al.
    KTH, School of Biotechnology (BIO), Industrial Biotechnology.
    Kayathri, Rajarathinam
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology.
    Murugan, Natarajan Arul
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology.
    Zhang, Qiong
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology.
    Srivastava, Vaibhav
    KTH, School of Biotechnology (BIO), Glycoscience.
    Okoli, Chuka
    KTH, School of Biotechnology (BIO), Industrial Biotechnology.
    Bulone, Vincent
    KTH, School of Biotechnology (BIO), Glycoscience.
    Rajarao, Gunaratna K.
    KTH, School of Biotechnology (BIO), Industrial Biotechnology.
    Ågren, Hans
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology.
    Dimerization of a flocculent protein from Moringa oleifera: experimental evidence and in silico interpretation2014In: Journal of Biomolecular Structure and Dynamics, ISSN 0739-1102, E-ISSN 1538-0254, Vol. 32, no 3, p. 406-415Article in journal (Refereed)
    Abstract [en]

    Many proteins exist in dimeric and other oligomeric forms to gain stability and functional advantages. In this study, the dimerization property of a coagulant protein (MO2.1) from Moringa oleifera seeds was addressed through laboratory experiments, protein-protein docking studies and binding free energy calculations. The structure of MO2.1 was predicted by homology modelling, while binding free energy and residues-distance profile analyses provided insight into the energetics and structural factors for dimer formation. Since the coagulation activities of the monomeric and dimeric forms of MO2.1 were comparable, it was concluded that oligomerization does not affect the biological activity of the protein.

  • 242.
    Pei, Aihua
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center.
    Berglund, Lars A.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology. KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center.
    Zhou, Qi
    KTH, School of Biotechnology (BIO), Glycoscience. KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center.
    Surface-modification of nanocelluloses and their applications in poly(lactic acid)/nanocellulose biocomposites2014In: Abstract of Papers of the American Chemical Society, ISSN 0065-7727, Vol. 247, p. 163-CELL-Article in journal (Other academic)
  • 243.
    Pei, Aihua
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Butchosa, Nuria
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Berglund, Lars A.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology. KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center.
    Zhou, Qi
    KTH, School of Biotechnology (BIO), Glycoscience. KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center.
    Surface quaternized cellulose nanofibrils with high water absorbency and adsorption capacity for anionic dyes2013In: Soft Matter, ISSN 1744-683X, E-ISSN 1744-6848, Vol. 9, no 6, p. 2047-2055Article in journal (Refereed)
    Abstract [en]

    Surface quaternized cellulose nanofibrils were mechanically disintegrated from wood pulp that was pretreated through a reaction with glycidyltrimethylammonium chloride. The resulting quaternized cellulose nanofibrils (Q-NFC) with trimethylammonium chloride contents of 0.59-2.31 mmol g(-1) were characterized by conductometric titration, X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), field emission scanning electron microscopy (FE-SEM), and atomic force microscopy (AFM). When the trimethylammonium chloride content on cellulose reached approximately 0.79 mmol g(-1) corresponding to a degree of substitution of 0.13 per bulk anhydroglucose unit, highly viscous and transparent aqueous dispersions of cellulose nanofibrils were obtained by mechanical homogenization of the chemically pretreated cellulose/water slurries. AFM observation showed that the dispersions consisted of individualized cellulose I nanofibrils 1.6-2.1 nm in width and 1.3-2.0 mu m in length. Cellulose nanopapers prepared from the Q-NFC aqueous dispersions exhibited high tensile strength (ca. 200 MPa) and Young's modulus (ca. 10 GPa) despite high porosity (37-48%). The nanopapers also demonstrated ultrahigh water absorbency (750 g g(-1)) with high surface cationic charge density. Stable hydrogels were obtained after swelling the nanopaper in water. The Q-NFC nanofibrils also possessed high anionic dye adsorption capability. The adsorption capacity increased with increasing trimethylammonium chloride content on cellulose.

  • 244.
    Pei, Aihua
    et al.
    KTH, School of Biotechnology (BIO).
    Malho, Jani-Markus
    Ruokolainen, Janne
    Zhou, Qi
    KTH, School of Biotechnology (BIO), Glycoscience.
    Berglund, Lars A.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Biocomposites.
    Strong Nanocomposite Reinforcement Effects in Polyurethane Elastomer with Low Volume Fraction of Cellulose Nanocrystals2011In: Macromolecules, ISSN 0024-9297, E-ISSN 1520-5835, Vol. 44, no 11, p. 4422-4427Article in journal (Refereed)
    Abstract [en]

    Polyurethane/cellulose nanocrystal nanocomposites with ultrahigh tensile strength and stain-to-failure with strongly improved modulus were prepared by adding cellulose nanocrystals (CNCs) during the preparation of prepolymer. The nanostructure of this polyurethane consisted of individualized nanocellulose crystals covalently bonded and specifically associated with the hard polyurethane (PU) microdomains as characterized by Fourier transform infrared spectroscopy and transmission electron microscopy. The storage modulus and thermal stability of the nanocomposites were significantly improved as measured by dynamic mechanical analysis. This was due to a combination of CNCs reinforcement in the soft matrix and increased effective cross-link density of the elastomer network due to CNC-PU molecular interaction. Tensile test revealed that the nanocomposites have both higher tensile strength and strain-to-failure. In particular, with only 1 wt % of cellulose nanocrystals incorporated, an 8-fold increase in tensile strength and 1.3-fold increase in strain-to-failure were achieved, respectively. Such high strength indicates that CNCs orient strongly at high strains and may also induce synergistic PU orientation effects contributing to the dramatic strength enhancement. The present elastomer nanocomposite outperforms conventional rubbery materials and polyurethane nanocomposites reinforced with microcrystalline cellulose, carbon nanotubes, or nanoclays.

  • 245.
    Pei, Aihua
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Biocomposites.
    Zhou, Qi
    KTH, School of Biotechnology (BIO), Glycoscience. KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Biocomposites.
    Berglund, Lars A.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Biocomposites. KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center.
    Functionalized cellulose nanocrystals as biobased nucleation agents in poly(L-lactide) (PLLA): Crystallization and mechanical property effects2010In: Composites Science And Technology, ISSN 0266-3538, E-ISSN 1879-1050, Vol. 70, no 5, p. 815-821Article in journal (Refereed)
    Abstract [en]

    The important industrial problem of slow crystallization of poly(l-lactide) (PLLA) is addressed by the use of cellulose nanocrystals as biobased nucleation reagents. Cellulose nanocrystals (CNC) were prepared by acid hydrolysis of cotton and additionally functionalized by partial silylation through reactions with n-dodecyldimethylchlorosilane in toluene. Such silylated cellulose nanocrystals (SCNC) were dispersible in tetrahydrofuran and chloroform, and formed stable suspensions. Nanocomposite films of PLLA and CNC or SCNC were prepared by solution casting. The effects of surface silylation of cellulose nanocrystals on morphology, non-isothermal and isothermal crystallization behavior, and mechanical properties of these truly nanostructured composites were investigated. The unmodified CNC formed aggregates in the composites, whereas the SCNC were well-dispersed and individualized in PLLA. As a result, the tensile modulus and tensile strength of the PLLA/SCNC nanocomposite films were more than 20% higher than for pure PLLA with only 1. wt.% SCNC, due to crystallinity effects and fine dispersion.

  • 246. Pelosi, Ludovic
    et al.
    Bulone, Vincent
    KTH, School of Biotechnology (BIO), Glycoscience.
    Heux, Laurent
    Polymorphism of curdlan and (1 -> 3)-beta-D-glucans synthesized in vitro: A C-13 CP-MAS and X-ray diffraction analysis2006In: Carbohydrate Polymers, ISSN 0144-8617, E-ISSN 1879-1344, Vol. 66, no 2, p. 199-207Article in journal (Refereed)
    Abstract [en]

    The polymorphism of three different forms of curdlan and four (1 -> 3)-beta-D-glucans synthesized in vitro was investigated by C-13 cross-polarization/magic angle spinning nuclear magnetic resonance (CP/MAS NMR) spectroscopy and X-ray powder diffraction. Dried samples of curdlan presented a disordered state whereas two distinct hydrated crystalline structures were evidenced for the polymer after hydrothermal treatment or swelling in water at room temperature. The samples synthesized in vitro by detergent extracts of plasma membranes from Rubus fruticosus and Saprolegnia monoica and by a mutated barley (1 -> 3)-beta-D-glucan endohydrolase exhibited a structural heterogeneity that can be explained in the light of the results obtained on standard samples. A 76-ppm resonance signal corresponding to carbon five was identified by CP/MAS NMR spectroscopy. The relative importance of this peak was shown to be linked to the proportion of the different crystalline allomorphs in a given sample. This peak can be considered as a new marker of the degree of organization of (1 -> 3)-beta-D-glucans. The observed polymorphism provides further detailed information on the conformation of the different (1 -> 3)P-D-glucan allomorphs.

  • 247.
    Piens, Kathleen
    et al.
    KTH, School of Biotechnology (BIO), Glycoscience.
    Fauré, Régis
    Centre de Recherche Sur Les Macromolécules Végétales, CNRS.
    Sundqvist, Gustav
    KTH, School of Biotechnology (BIO), Glycoscience.
    Baumann, Martin J.
    KTH, School of Biotechnology (BIO), Glycoscience.
    Saura-Valls, Marc
    Laboratory of Biochemistry, Institut Químic de Sarrià, Universitat Ramon Llull.
    Teeri, Tuula T.
    KTH, School of Biotechnology (BIO), Glycoscience.
    Cottaz, Sylvain
    Centre de Recherche Sur Les Macromolécules Végétales, CNRS.
    Planas, Antoni
    Laboratory of Biochemistry, Institut Químic de Sarrià, Universitat Ramon Llull.
    Driquez, Hugues
    Centre de Recherche Sur Les Macromolécules Végétales, CNRS.
    Brumer, Harry
    KTH, School of Biotechnology (BIO), Glycoscience.
    Mechanism-based labeling defines the free energy change for formation of the covalent glycosyl-enzyme intermediate in a xyloglucan endo-transglycosylase2008In: Journal of Biological Chemistry, ISSN 0021-9258, E-ISSN 1083-351X, Vol. 283, no 32, p. 21864-21872Article in journal (Refereed)
    Abstract [en]

    Xyloglucan endo-transglycosylases (XETs) are key enzymes involved in the restructuring of plant cell walls during morphogenesis. As members of glycoside hydrolase family 16 (GH16), XETs are predicted to employ the canonical retaining mechanism of glycosyl transfer involving a covalent glycosyl-enzyme intermediate. Here, we report the accumulation and direct observation of such intermediates of PttXET16-34 from hybrid aspen by electrospray mass spectrometry in combination with synthetic "blocked" substrates, which function as glycosyl donors but are incapable of acting as glycosyl acceptors. Thus, GalGXXXGGG and GalGXXXGXXXG react with the wild-type enzyme to yield relatively stable, kinetically competent, covalent GalG-enzyme and GalGXXXG-enzyme complexes, respectively (Gal = Gal beta(1 -> 4), G = Glc beta(1 -> 4), and X = Xyl alpha(1 -> 6) Glc beta(1 -> 4)). Quantitation of ratios of protein and saccharide species at pseudo-equilibrium allowed us to estimate the free energy change (Delta G(0)) for the formation of the covalent GalGXXXG-enzyme as 6.3-8.5 kJ/mol (1.5-2.0 kcal/mol). The data indicate that the free energy of the beta(1 -> 4) glucosidic bond in xyloglucans is preserved in the glycosyl-enzyme intermediate and harnessed for religation of the polysaccharide in vivo.

  • 248.
    Piens, Kathleen
    et al.
    KTH, School of Biotechnology (BIO), Glycoscience.
    Henriksson, Maria
    KTH, School of Biotechnology (BIO).
    Gullfot, Fredrika
    Lopez, Marie
    Fauré, Régis
    Ibatullin, Farid M.
    KTH, School of Biotechnology (BIO), Glycoscience.
    Teeri, Tuula T.
    KTH, School of Biotechnology (BIO), Glycoscience.
    Driguez, Hugues
    Brumer, Harry
    KTH, School of Biotechnology (BIO), Glycoscience.
    Glycosynthase activity of hybrid aspen xyloglucan endo-transglycosylase PttXET16-34 nucleophile mutants2007In: Organic and Biomolecular Chemistry, ISSN 1477-0520, Vol. 5, no 24Article in journal (Refereed)
    Abstract [en]

    Glycosynthases are active-site mutants of glycoside hydrolases that catalyse glycosyl transfer using suitable activated donor substrates without competing product hydrolysis ( S. M. Hancock, M. D. Vaughan and S. G. Withers, Curr. Opin. Chem. Biol., 2006, 10, 509-519). Site-directed mutagenesis of the catalytic nucleophile, Glu-85, of a Populus tremula x tremuloides xyloglucan endo-transglycosylase (PttXET16-34, EC 2.4.1.207) into alanine, glycine, and serine yielded enzymes with glycosynthase activity. Product analysis indicated that PttXET16-34 E85A in particular was able to catalyse regio- and stereospecific homo- and hetero- condensations of alpha-xylogluco-oligosaccharyl fluoride donors XXXG alpha F andXLLG alpha F to produce xyloglucans with regular sidechain substitution patterns. This substrate promiscuity contrasts that of the Humicola insolens Ce17B E197A glycosynthase, which was not able to polymerise the di-galactosylated substrate XLLG alpha F. The production of the PttXET16-34 E85A xyloglucosynthase thus expands the repertoire of glycosynthases to include those capable of synthesising structurally homogenenous xyloglucans

  • 249. Pisanelli, I.
    et al.
    Kujawa, M.
    Gschnitzer, D.
    Spadiut, Oliver
    KTH, School of Biotechnology (BIO), Glycoscience. University of Natural Resources and Applied Life Sciences (BOKU), Vienna, Austria .
    Seiboth, B.
    Peterbauer, C.
    Heterologous expression of an Agaricus meleagris pyranose dehydrogenase-encoding gene in Aspergillus spp. and characterization of the recombinant enzyme2010In: Applied Microbiology and Biotechnology, ISSN 0175-7598, E-ISSN 1432-0614, Vol. 86, no 2, p. 599-606Article in journal (Refereed)
    Abstract [en]

    Pyranose dehydrogenase (PDH) is a flavin-dependant sugar oxidoreductase found in the family Agaricaceae, basidiomycetes that degrade lignocellulose-rich forest litter, and is catalytically related to the fungal enzymes pyranose 2-oxidase and cellobiose dehydrogenase. It has broad substrate specificity and displays similar activities with most sugar constituents of lignocellulose including disaccharides and oligosaccharides, a number of (substituted) quinones, and metal ions are suitable electron acceptors rather than molecular oxygen. In contrast to pyranose 2-oxidase and cellobiose dehydrogenase, which oxidize regioselectively at C-2 and C-1, respectively, PDH is capable of oxidation on C-1 to C-4 as well as double oxidations, depending on the nature of the substrate. This makes it a very interesting enzyme for biocatalytic applications, as many of the reaction products are otherwise unaccessible by chemical or enzymatic means. PDH was characterized in detail in a limited number of fungi, and the first encoding genes were isolated only recently. We report here, for the first time, the heterologous expression of one of these genes, encoding the major PDH protein in Agaricus meleagris, in the filamentous fungi Aspergillus nidulans, and Aspergillus niger.

  • 250. Pitsawong, Warintra
    et al.
    Sucharitakul, Jeerus
    Prongjit, Methinee
    Tan, Tien-Chye
    KTH, School of Biotechnology (BIO), Glycoscience.
    Spadiut, Oliver
    KTH, School of Biotechnology (BIO), Glycoscience.
    Haltrich, Dietmar
    Divne, Christina
    KTH, School of Biotechnology (BIO), Glycoscience.
    Chaiyen, Pimchai
    A Conserved Active-site Threonine Is Important for Both Sugar and Flavin Oxidations of Pyranose 2-Oxidase2010In: Journal of Biological Chemistry, ISSN 0021-9258, E-ISSN 1083-351X, Vol. 285, no 13, p. 9697-9705Article in journal (Refereed)
    Abstract [en]

    Pyranose 2-oxidase (P2O) catalyzes the oxidation by O-2 of D-glucose and several aldopyranoses to yield the 2-ketoaldoses and H2O2. Based on crystal structures, in one rotamer conformation, the threonine hydroxyl of Thr(169) forms H-bonds to the flavin-N5/O4 locus, whereas, in a different rotamer, it may interact with either sugar or other parts of the P2O center dot sugar complex. Transient kinetics of wild-type (WT) and Thr(169)-> S/N/G/A replacement variants show that D-Glc binds to T169S, T169N, and WT with the same K-d (45-47 mM), and the hydride transfer rate constants (k(red)) are similar (15.3-9.7 s(-1) at 4 degrees C). k(red) of T169G with D-glucose (0.7 s(-1), 4 degrees C) is significantly less than that of WT but not as severely affected as in T169A (k(red) of 0.03 s(-1) at 25 degrees C). Transient kinetics of WT and mutants using D-galactose show that P2O binds D-galactose with a one-step binding process, different from binding of D- glucose. In T169S, T169N, and T169G, the overall turnover with D- Gal is faster than that of WT due to an increase of kred. In the crystal structure of T169S, Ser(169) O gamma assumes a position identical to that of O gamma 1 in Thr(169); in T169G, solvent molecules may be able to rescue H-bonding. Our data suggest that a competent reductive half-reaction requires a side chain at position 169 that is able to form an H-bond within the ES complex. During the oxidative half-reaction, all mutants failed to stabilize a C4a-hydroperoxyflavin intermediate, thus suggesting that the precise position and geometry of the Thr(169) side chain are required for intermediate stabilization.

234567 201 - 250 of 350
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